1. Technical Field
The present invention relates to a manufacturing method of a semiconductor device and a semiconductor device manufacturing apparatus for forming a diffusion layer by diffusing phosphorus atoms on a surface of a silicon substrate.
2. Background Art
As an example of a semiconductor device, a planar type FET (Field Effect Transistor) is manufactured, so that source, drain, and channel are formed directly on a flat silicon substrate for example, and a flat gate and a gate electrode are formed on the channel. Then, in a case of a FET device called NMOS, phosphorus atoms, for example, are diffused on the aforementioned channel as impurities for making a current easy to flow.
As a diffusion method of the phosphorus atoms, conventionally, an ion injection method is used wherein the phosphorous atoms are ionized to generate ion beam, which is then injected into a silicon substrate. The ion injection method has an advantage that an injection amount of ions can be controlled by a current amount of the ion beam and a depth of ion injection can be controlled by acceleration energy (acceleration voltage) of the ion beam.
However, when a size of a semiconductor device is reduced along with a high integration, the source, drain, and channel also tend to become thinner. At this time, adjustment is required, to achieve extremely shallow ion injection. However, in a conventional technique of the ion injection, the ion beam accelerated once needs to be decelerated again, and this is disadvantageous in terms of cost and throughput.
In addition, when a three-dimensional construction of a device structure is progressed along with the high integration of the semiconductor device, for example, the channel also needs to be three-dimensionally constructed. When the channel is three-dimensionally constructed, the ions must be injected not only from a vertical direction but also from a lateral direction. However, the ion injection method has strong anisotropy and is disadvantageous for injecting ions uniform both vertically and laterally.
Therefore, instead of the conventional ion injection method, a diffusion method of phosphorus atoms by using plasma has been performed. The diffusion method of phosphorus atoms by using plasma is advantageous, because the phosphorus atoms can be diffused shallow and uniform both vertically and laterally.